2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
FOREWORDLRFD Guide Specifications for Design of Concrete-Filled FRP Tubes for Flexural and Axial Members, First Edition(2012) was developed as a collaborative effort between Dr. Amir Fam of Queen’s University, Ontario, the University ofMaine, and Advanced Infrastructure Technologies with review and approval by the AASHTO T-6 TechnicalSubcommittee for Fiber-Reinforced Polymer Composites.The basis of this document was derived from a large body of research published over the past 15 years by a variety ofresearch institutions. These resources can be found in the references sections of this document.AASHTO Subcommittee on Bridges and Structuresv 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
PREFACEThis new AASHTO publication, LRFD Guide Specifications for Design of Concrete-Filled FRP Tubes for Flexural andAxial Members, First Edition (2012), comprises three sections:Section 1—IntroductionSection 2—Concrete-Filled FRP Tubes (CFFTs)Section 3—Material SpecificationsA list of references is included at the end of each section.AASHTO Publications StaffDecember 2012vii 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
SECTION 1: INTRODUCTIONTABLE OF CONTENTS1.1—SCOPE . 1-11.2—DEFINITIONS. 1-11.3—LIMITATIONS . 1-21.4—DESIGN PHILOSOPHY . 1-21.5—REFERENCES . 1-21-i 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
SECTION 2: CONCRETE-FILLED FRP TUBES (CFFTS)TABLE OF CONTENTS2.1—SCOPE . 2-12.2—DEFINITIONS. 2-12.3—NOTATION . 2-12.4—LIMITATIONS . 2-32.5—VERIFICATION OF COMPOSITE ACTION . 2-32.6—MATERIAL PROPERTIES . 2-42.6.1—FRP Tube . 2-184.108.40.206—General. 2-220.127.116.11—Tensile and Compressive Ultimate Strengths and Strains . 2-18.104.22.168—Modulus of Elasticity . 2-52.7—LIMIT STATES . 2-52.7.1—Service Limit State. 2-52.7.2—Fatigue and Creep Rupture Limit State. 2-52.7.3—Strength Limit State . 2-22.214.171.124—General. 2-126.96.36.199—Resistance Factors . 2-188.8.131.52—Stability. 2-82.7.4—Extreme Event Limit State . 2-82.8—DESIGN CONSIDERATIONS . 2-82.8.1—General. 2-82.8.2—Effect of Imposed Deformation . 2-82.9—DESIGN FOR FLEXURE WITH NO AXIAL COMPRESSION . 2-82.9.1—General. 2-82.9.2—Assumptions . 2-184.108.40.206—General. 2-220.127.116.11—Service and Fatigue and Creep Rupture Limit States . 2-18.104.22.168—Strength and Extreme Event Limit States . 2-92.9.3—Minimum Longitudinal Tension Reinforcement . 2-102.9.4—Minimum Reinforcement in the Transverse or Hoop Direction . 2-102.9.5—Factored Flexural Resistance . 2-22.214.171.124—General Method . 2-126.96.36.199—Simplified Method . 2-112.9.6—Deformation . 2-112.9.7—Control of Cracking . 2-112.9.8—Stress Limit for Concrete . 2-112.10—DESIGN FOR AXIAL COMPRESSION . 2-112.10.1—General . 2-112.10.2—Assumptions . 2-122-i 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
2-iiLRFD GUIDE SPECIFICATIONS FOR DESIGN OF CONCRETE-FILLEDFRP TUBES FOR FLEXURAL AND AXIAL MEMBERS, 1ST EDITION2.10.3—Factored Axial Compressive Resistance .2-122.10.4—Minimum Reinforcement in the Hoop Direction .2-142.10.5—Stress Limit for Concrete .2-142.11—DESIGN FOR COMBINED FLEXURE AND AXIAL COMPRESSION .2-142.11.1—General .2-142.11.2—Assumptions .2-152.11.3—Factored Resistance .2-188.8.131.52—General Method .2-184.108.40.206—Simplified Method .2-162.11.4—Evaluation of Slenderness Effects .2-172.11.5—Minimum Reinforcement .2-172.11.6—Deformation .2-172.11.7—Control of Cracking.2-172.11.8—Stress Limit for Concrete .2-172.12—DESIGN FOR SHEAR EFFECTS .2-182.12.1—General .2-182.12.2—Nominal Shear Resistance.2-182.12.3—Minimum Shear Reinforcement .2-202.13—CONNECTIONS.2-202.14—REFERENCES .2-21 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
SECTION 3: MATERIAL SPECIFICATIONSTABLE OF CONTENTS3.1—SCOPE . 3-13.2—DEFINITIONS. 3-13.3—NON-STANDARD DOCUMENTS . 3-23.4—MATERIAL AND MANUFACTURE . 3-23.4.1—Fibers . 3-23.4.2—Matrix Resins . 3-33.4.3—Fillers and Additives . 3-33.4.4—Manufacturing Process . 3-33.5—PHYSICAL PROPERITES. 3-33.5.1—Fiber Content . 3-33.5.2—Glass Transition Temperature . 3-33.5.3—Longitudinal and Transverse Coefficients of Thermal Expansion (CTE). 3-43.6—MECHANICAL PROPERTIES . 3-43.6.1—Tensile Strength . 3-43.6.2—Tensile Modulus of Elasticity . 3-43.6.3—Ultimate Tensile Strain . 3-53.6.4—Compressive Strength . 3-53.6.5—Ultimate Compressive Strain . 3-53.7—DURABILITY PROPERTIES . 3-63.7.1—Moisture Absorption . 3-63.7.2—Resistance to Alkaline Environment . 3-63.8—SAMPLING . 3-63.8.1—Sampling Frequency and Number of Specimens . 3-63.8.2—Rejection . 3-63.9—CERFTIFICATION . 3-73.9.1—Documents . 3-73.9.2—QC/QA . 3-73.9.3—Product Certification . 3-73.9.4—Markings . 3-83.10—REFERENCES . 3-83-i 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
SECTION 1INTRODUCTION1.1—SCOPEC1.1These Specifications present provisions for theanalysis and design of concrete-filled fiber-reinforcedpolymer (FRP) tubes (CFFT) for use as structuralcomponents in bridges. Design methodology presented inthis specification allows CFFTs to be designed asflexural members, axial compression members, ormembers subjected to combined flexural and axialcompression, in addition to shear. CFFT bridgecomponents may include beams, arches, columns, andpiles.FRP materials have emerged as an alternativematerial to steel reinforcement for concrete structures.They offer advantages over steel reinforcement due totheir noncorrosive nature and nonconductive behavior.FRP is a also a versatile material that can be produced inmany forms such as reinforcing bars, grids, rigid plates,flexible sheets, and several structural shapes, includingtubes. This specification is focused on one application ofFRP in the form of tubes used as structural stay-in-placeforms filled with concrete [Fardis and Khalili (1981),Nanni and Bradford (1995), Mirmiran and Shahawy(1996), Davol (1998), Burgueño (1999), Fam (2000),Fam and Rizkalla (2001), Fam and Rizkalla (2002)]. Dueto differences in the physical and mechanical behavior ofFRP materials as opposed to steel, particularly whenused as stay-in-place structural forms, unique guidanceon the engineering and construction of bridgecomponents using this technology is needed.These Specifications are not intended to supplantproper training or the exercise of judgment by the DesignProfessional, and state only the minimum requirementsnecessary to provide public safety. The Owner or theDesign Professional may require the sophistication of thedesign or the quality of materials and construction, orboth, to be higher than the minimum requirements.The Design Professional shall be familiar with theprovisions of the AASHTO LRFD Bridge DesignSpecifications, 6th Edition (AASHTO, 2012), hereafterreferred to as “AASHTO LRFD,” and the latest interimrevisions, as well as with the design of conventionalreinforced concrete structures and structures exposed toearth loading.The commentary directs attention to otherdocuments that provide suggestions for carrying out therequirements and intent of these Specifications.However, those documents and this commentary are notintended to be a part of these Specifications.1.2—DEFINITIONSComposite Action—A condition in which two or more elements or components are made to act together byeliminating relative movements at their interface.Design Professional—The architect, engineer, architectural firm, or engineering firm responsible for the design of thebridge and issuing Contract Documents or administering the Work under Contract Documents, or both.Fiber—Any fine thread-like natural or synthetic object of mineral or organic origin. Note: This term is generally usedfor materials whose length is at least 100 times its diameter.Fiber, Aramid—Highly oriented organic fiber derived from polyamide incorporating an aromatic ring structure.Fiber, Carbon—Fiber produced by heating organic precursor materials containing a substantial amount of carbon,such as rayon, polyacrylonitrile (PAN), or pitch in an inert environment.1-1 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.
LRFD GUIDE SPECIFICATIONS FOR DESIGN OF CONCRETE-FILLEDFRP TUBES FOR FLEXURAL AND AXIAL MEMBERS, 1ST EDITION1-2Fiber, Glass—Fiber drawn from an inorganic product of fusion that has cooled without crystallizing.1.3—LIMITATIONSC1.3Composite action between the concrete core andFRP tube is required for a CFFT member to develop itsstiffness and strength as defined in these Specifications.CFFTs that do not have sufficient bond between theconcrete core and FRP tube to ensure composite actionare not addressed in these Specifications. Compositeaction shall be verified in accordance with Article 2.5.The assumed failure mechanism of CFFTs used asflexural members shall not be based on the formation ofplastic hinges. CFFTs shall not be used as ductileearthquake resisting elements.Bond may be achieved by shear interlockmechanism, such as a roughened inner surface of theFRP tube or friction, or both, that can be furtherenhanced by the use of low-shrinkage or expansiveconcrete. FRP materials demonstrate a linear-elasticbehavior up to failure and do not demonstrate yielding,which is the basis for plastic hinge formation andmoment redistribution.1.4—DESIGN PHILOSOPHYC1.4These Specifications are based on limit state designprinciples where structural components shall beproportioned to satisfy the requirements at all appropriateservice, fatigue and creep rupture, strength, and extremeevent limit states. In many instances, serviceability orfatigue and creep rupture limits may control the design.Provisions related to limit states analyses, generaldesign and location features, loads and load factors, andstructural analysis and evaluation shall be in compliancewith AASHTO LRFD.The limit states specified herein are intended toprovide for a buildable, serviceable bridge, capable ofsafely carrying design loads for a specified lifetime.1.5—REFERENCESAASHTO. 2012. AASHTO LRFD Bridge Design Specifications, 6th Edition with Interims, American Association ofState Highway and Transportation Officials, Washington DC.Burgueño, R. 1999. “System Characterization and Design of Modular Fiber Reinforced Polymer (FRP) Short- andMedium-Span Bridges,” Doctoral dissertation, UMI No. 9928617, University of California, San Diego, CA.Davol, A. 1998. “Structural Characterization of Concrete Filled Fiber Reinforced Shells,” Doctoral dissertation,University of California, San Diego, CA.Fam, A. 2000. “Concrete-Filled Fibre-Reinforced Polymer Tubes for Axial and Flexural Structural Members.”Doctoral dissertation, Univeristy of Manitoba. Winnepeg, Manitoba, Canada.Fam, A. and S. Rizkalla. 2001. “Confinement Model for Axially Loaded Concrete Confined by Circular FiberReinforced Polymer Tubes,” ACI Structural Journal 98(4), pp. 451–461. American Concrete Institute, FarmingtonHills, MI.Fam, A. and S. Rizkalla. 2002. “Flexural Behavior of Concrete-Filled Fiber-Reinforced Polymer Circular Tubes,”Journal of Composites for Construction, 6(2), pp. 123–132. American Society of Civil Engineers, Reston, VA.Fardis, M. N. and H. Khalili. November–December 1981. “Concrete Encased in Fibreglass-Reinforced Plastic,” ACIStructural Journal, Title No. 78-38, pp. 440–446. American Concrete Institute, Farmington Hills, MI.Mirmiran, A. and M. Shahawy. 1996. “A New Concrete-Filled Hollow FRP Composite Column,” Composites PartB: Engineering, Special Issue on Infrastructure, Elsevier Science Ltd., 27B (3–4), pp. 263–268. Elsevier, Amsterdam,The Netherlands.Nanni, A. and N. Bradford. 1995. “FRP Jacketed Concrete under Uniaxial Compression,” Construction and BuildingMaterials, 9(2), pp. 115–124. Elsevier, Amsterdam, The Netherlands. 2012 by the American Association of State Highway and Transportation Officials.All rights reserved. Duplication is a violation of applicable law.